Maraschino cherries are an artificially colored and flavored fruit product made from whole cherry fruit. The harvested cherries are placed into a sulfur dioxide brine and held there until processed. The brine serves the dual function of bleaching the color from the fruit and of preserving the fruit until it is needed for processing.
The first step in processing is to remove sulfur dioxide from the fruit. This is generally accomplished by leaching the cherries in running water for a period of time to reduce the sulfur dioxide content to an acceptable level. Applied heat can also be used to speed the process, although this can be detrimental to final texture. Boiling water leaches have been used for this purpose. A residual sulfur dioxide level of 100 ppm or less is acceptable for proper color set in the cherry.
After leaching, the soluble solids level remaining in the cherries is generally quite low, in the range of 1.degree. to 5.degree. Brix. While there is some cherry flavor remaining, there is little left of the original fruit save for the form and structure. The next step in the process is to build the soluble solids level in the fruit to a level of about 40.degree. Brix, and color the fruit at the same time to a uniform red color. Glace cherries have soluble solids built to about 70%. This "sugaring" or "syruping" process is accomplished by immersing the fruit into a syrup for a period of time to allow the syrup solids to diffuse into the fruit. The prime concern at this point is to avoid shrinking or shrivelling of the fruit, which represents a yield loss.
To avoid yield losses, both the type of syrup used and its concentration are important. For cost reasons, a typical syrup used is composed of equal amounts of a high fructose corn syrup (HFCS) and a regular conversion corn syrup. The HFCS is used to provide sweetness while the regular corn syrup is present to provide body and texture.